1. Technical Field
The present invention relates to an in-vehicle communication system that is configured to connect a short range wireless communication link between an in-vehicle apparatus and a portable device so that the short range wireless communication link enables a passenger to control the portable device by manipulating the in-vehicle apparatus. The present invention also relates to an in-vehicle apparatus usable in the in-vehicle communication system.
2. Description of Related Art
For example, Patent Document 1 discloses a system configured to automatically establish a short range wireless communication link between an in-vehicle apparatus mounted to a vehicle and a portable device capable of being carried by a passenger when the portable device is carried into a vehicle compartment of the vehicle, and when the in-vehicle apparatus and the portable device are within a wireless communication range (i.e., a range that allows the in-vehicle apparatus and the portable device to communicate with each other).
Patent Document 1: JP-2002-193046A corresponding to US/20020032048A
In a system like the above system, an in-vehicle apparatus and a portable device can cooperate with each other by establishing a short range wireless communication link therebetween, so that a passenger can control an operation of the portable device by manipulating the in-vehicle apparatus. For example, when a phone book data (e.g., phone book list) is transferred from the portable device to the in-vehicle apparatus and the phone book list is displayed on a display device of the in-vehicle apparatus, a passenger can search for a certain phone number by manipulating the phone number list displayed on the display device of the in-vehicle apparatus. Moreover, the passenger can make a phone call from the portable device by pressing an outgoing call button that is formed on the display device of the in-vehicle apparatus as a touch sensitive switch.
In this relation, while the portable device and the in-vehicle apparatus are being connected with each other via the short range wireless communication link, each of the portable device and the in-vehicle apparatus keeps consuming an electric power due to the connection of the short range wireless communication link even if there is no passenger's manipulation on the portable device or the in-vehicle apparatus. In this relation, the electric power consumption of the in-vehicle apparatus caused by the short range wireless communication link involves no disadvantage since the in-vehicle apparatus operates on an electric power supplied from a vehicle battery mounted to the vehicle. In contrast, since the portable device operates on an electric power supplied from its detachable battery, a battery level of the portable device keeps deceasing when the portable device has the short range wireless communication link with the in-vehicle apparatus.
If the portable device is put in, for example, a passenger's pocket of a jacket or a bag, the passenger cannot recognize the battery level (i.e., reaming battery level). As a result, when the portable device and the in-vehicle apparatus are connected with each other via a short range wireless communication link, the battery level decreases to below a threshold to make the portable device unusable. In this case, the passenger may become aware that the portable device is unusable only when the passenger gets out of the vehicle. In particular, since the system is configured to enable a passenger to control the portable device by manipulating the in-vehicle apparatus, it is conceivable that the passenger may rarely manipulate the portable device. Thus, it is difficult for the passenger to be aware of the decrease in battery level of the portable device.